Manufacturing method of ceramic electronic device

ABSTRACT

A manufacturing method of a ceramic electronic device includes: preparing a ceramic electronic device having a multilayer chip, a first external electrode, and a second external electrode, and bonding an organic compound having a siloxane bonding to at least a part of a region including a surface of the multilayer chip where neither the first external electrode nor the second external electrode is formed and surfaces of the first external electrode and the second external electrode, by contacting heated silicon rubber to the region.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.16/737,619, filed Jan. 8, 2020, which is based upon and claims thebenefit of priority of the prior Japanese Patent Application PublicationNo. 2019-007723, filed on Jan. 21, 2019 and Japanese Patent ApplicationNo. 2019-174522, filed on Sep. 25, 2019, each disclosure of which isherein incorporated by reference in its entirety. The applicant hereinexplicitly rescinds and retracts any prior disclaimers or disavowals orany amendment/statement otherwise limiting claim scope made in anyparent, child or related prosecution history with regard to any subjectmatter supported by the present application.

FIELD

A certain aspect of the present invention relates to a ceramicelectronic device and a manufacturing method of the ceramic electronicdevice.

BACKGROUND

For example, an external electrode of a ceramic electronic device suchas a multilayer ceramic capacitor has a conductive resin layer in whicha metal component and resin are mixed, in order to suppress stress whenmounting the ceramic electronic device on a substrate (for example, seeJapanese Patent Application Publication No. 2016-63008).

SUMMARY OF THE INVENTION

When the ceramic electronic device is used in high-temperature andhigh-humidity condition, the metal component of the conductive resinlayer may diffuse because of water adhered to a surface of the ceramicelectronic device. In this case, reliability of the ceramic electronicdevice may be degraded. Even if the external electrode does not have theconductive resin layer, a metal component of the external electrode maydiffuse and the reliability may be degraded.

The present invention has a purpose of providing a ceramic electronicdevice and a manufacturing method of the ceramic electronic device thatare capable of improving reliability of the ceramic electronic device.

According to an aspect of the present invention, there is provided aceramic electronic device including: a multilayer chip in which each ofa plurality of dielectric layers and each of a plurality of internalelectrode layers are alternately stacked, a main component of thedielectric layers being ceramic, the multilayer chip having arectangular parallelepiped shape, the plurality of internal electrodelayers being alternately exposed to a first end face and a second endface of the multilayer chip, the first end face facing with the secondend face, a first external electrode provided on the first end face; asecond external electrode provided on the second end face; and anorganic compound that is adhered to at least a part of a regionincluding a surface of the multilayer chip where neither the firstexternal electrode nor the second external electrode is formed andsurfaces of the first external electrode and the second externalelectrode, and has a siloxane bonding.

According to another aspect of the present invention, there is provideda manufacturing method of a ceramic electronic device including;preparing a ceramic electronic device having a multilayer chip, a firstexternal electrode and a second external electrode, bonding an organiccompound having a siloxane bonding to at least a part of a regionincluding a surface of the multilayer chip where neither the firstexternal electrode nor the second external electrode is formed andsurfaces of the first external electrode and the second externalelectrode, by contacting heated silicon rubber to the region, whereinthe multilayer chip has a structure in which each of a plurality ofdielectric layers and each of a plurality of internal electrode layersare alternately stacked, a main component of the dielectric layers beingceramic, the multilayer chip having a rectangular parallelepiped shape,the plurality of internal electrode layers being alternately exposed toa first end face and a second end face of the multilayer chip, the firstend face facing with the second end face, wherein the first externalelectrode is provided on the first end face, therein the second externalelectrode provided on the second end face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a multilayer ceramic capacitorin which a cross section of a part of the multilayer ceramic capacitoris illustrated;

FIG. 2 illustrates a cross sectional view of an external electrode andis a partial cross sectional view taken along a line A-A of FIG. 1 ;

FIG. 3 illustrates a structure in which an organic compound is adheredto a multilayer ceramic capacitor;

FIG. 4 illustrates a structure in which a silane film and an organiccompound are provided on a multilayer ceramic capacitor;

FIG. 5 illustrates a manufacturing method of a multilayer ceramiccapacitor;

FIG. 6 illustrates a manufacturing method of a multilayer ceramiccapacitor;

FIG. 7 illustrates a case where a silicon sheet is pressed to amultilayer ceramic capacitor; and

FIG. 8 illustrates analysis results of a cyclic siloxane.

DETAILED DESCRIPTION

A description will be given of an embodiment with reference to theaccompanying drawings.

Embodiment

A description will be given of an outline of a multilayer ceramiccapacitor. FIG. 1 illustrates a perspective view of a multilayer ceramiccapacitor 100 in accordance with an embodiment, in which a cross sectionof a part of the multilayer ceramic capacitor 100 is illustrated. Asillustrated in FIG. 1 , the multilayer ceramic capacitor 100 includes amultilayer chip 10 having a rectangular parallelepiped shape, and a pairof external electrodes 20 a and 20 b that are respectively provided attwo end faces of the multilayer chip 10 facing each other. In four facesother than the two end faces of the multilayer chip 10, two faces otherthan an upper face and a lower face of the multilayer chip 10 in astacking direction are referred to as side faces. The externalelectrodes 20 a and 20 b extend to the upper face, the lower face andthe two side faces of the multilayer chip 10. However, the externalelectrodes 20 a and 20 b are spaced from each other.

The multilayer chip 10 has a structure designed to have dielectriclayers 11 and internal electrode layers 12 alternately stacked. Thedielectric layer 11 includes ceramic material acting as a dielectricmaterial. The internal electrode layers 12 include a base metalmaterial. End edges of the internal electrode layers 12 are alternatelyexposed to a first end face of the multilayer chip 10 and a second endface of the multilayer chip 10 that is different from the first endface. In the embodiment, the first end face faces with the second endface. The external electrode 20 a is provided on the first end face. Theexternal electrode 20 b is provided on the second end face. Thus, theinternal electrode layers 12 are alternately conducted to the externalelectrode 20 a and the external electrode 20 b. Thus, the multilayerceramic capacitor 100 has a structure in which a plurality of dielectriclayers 11 are stacked and each two of the dielectric layers 11 sandwichthe internal electrode layer 12. In a multilayer structure of thedielectric layers 11 and the internal electrode layers 12, the internalelectrode layer 12 is positioned at an outermost layer in a stackingdirection. The upper face and the lower face of the multilayer structurethat are the internal electrode layers 12 are covered by cover layers13. A main component of the cover layer 13 is a ceramic material. Forexample, a main component of the cover layer 13 is the same as that ofthe dielectric layer 11.

For example, the multilayer ceramic capacitor 100 may have a length of0.25 mm, a width of 0.125 mm and a height of 0.125 mm. The multilayerceramic capacitor 100 may have a length of 0.4 mm, a width of 0.2 mm anda height of 0.2 mm. The multilayer ceramic capacitor 100 may have alength of 0.6 mm, a width of 0.3 mm and a height of 0.3 mm. Themultilayer ceramic capacitor 100 may have a length of 1.0 mm, a width of0.5 mm and a height of 0.5 mm. The multilayer ceramic capacitor 100 mayhave a length of 3.2 mm, a width of 1.6 mm and a height of 1.6 mm. Themultilayer ceramic capacitor 100 may have a length of 4.5 mm, a width of3.2 mm and a height of 2.5 mm. However, the size of the multilayerceramic capacitor 100 is not limited.

A main component of the internal electrode layers 12 is a base metalsuch as nickel (Ni), copper (Cu), tin (Sn) or the like. The internalelectrode layers 12 may be made of a noble metal such as platinum (Pt),palladium (Pd), silver (Ag), gold (Au) or alloy thereof. The dielectriclayers 11 are mainly composed of a ceramic material that is expressed bya general formula ABO₃ and has a perovskite structure. The perovskitestructure includes ABO_(3-α) having an off-stoichiometric composition.For example, the ceramic material is such as BaTiO₃ (barium titanate),CaZrO₃ (calcium zirconate), CaTiO₃ (calcium titanate), SrTiO₃ (strontiumtitanate), Ba_(1-x-y)Ca_(x)Sr_(y)Ti_(1-z)Zr_(z)O₃ (0≤x≤1, 0≤y≤1, 0≤z≤1)having a perovskite structure.

FIG. 2 illustrates a cross sectional view of the external electrode 20 band is a partial cross sectional view taken along a line A-A of FIG. 1 .In FIG. 2 , hatching for cross section is omitted. As illustrated inFIG. 2 , the external electrode 20 b has a structure in which a firstplated layer 22 such as Cu, a conductive resin layer 23, a second platedlayer 24 such as Ni and a third plated layer 25 such as Sn are formed ona ground layer 21 in this order. The ground layer 21, the first platedlayer 22, the conductive resin layer 23, the second plated layer 24 andthe third plated layer 25 extend toward the four side faces of themultilayer chip 10 from the both end faces of the multilayer chip 10.

A main component of the ground layer 21 is a metal such as Cu, Ni, Al(aluminum) or Zn (zinc). The ground layer 21 includes a glass componentfor densifying the ground layer 21 or a co-material for controllingsinterability of the ground layer 21. The ground layer 21 includingthese ceramic components has high adhesiveness with the cover layer 13whose main component is a ceramic material. The conductive resin layer23 is a resin layer including a metal component such as Ag. Theconductive resin layer 23 is flexible. Therefore, the conductive resinlayer 23 suppresses stress caused by deflection of a substrate on whichthe multilayer ceramic capacitor 100 is mounted. The first plated layer22 is provided in order to increase adhesiveness between the groundlayer 21 and the conductive resin layer 23. The external electrode 20 ahas the same structure as the external electrode 20 b. The conductiveresin layer 23 may not be necessarily provided.

When the external electrodes 20 a and 20 b have the structureillustrated in FIG. 2 and the multilayer ceramic capacitor 100 is usedin high-temperature and high-humidity condition, a metal component ofthe conductive resin layer 23 may diffuse because of water adhered tothe surface of the multilayer ceramic capacitor 100. In this case,reliability of the multilayer ceramic capacitor 100 may be degraded. Forexample, the metal component of the conductive resin layer 23 maydiffuse to the surface of the multilayer chip 10 between the externalelectrode 20 a and the external electrode 20 b (migration phenomena).Even if the external electrodes 20 a and 20 b do not include theconductive resin layer 23, another metal component of the externalelectrodes 20 a and 20 b may diffuse.

And so, the multilayer ceramic capacitor 100 of the embodiment has astructure in which an organic compound 14 having siloxane bonding isadhered to at least a part of the surface of the multilayer ceramiccapacitor 100, as illustrated in FIG. 3 . That is, the organic compound14 is adhered to at least a part of a region including the surface ofthe multilayer chip 10 where the external electrodes 20 a and 20 b arenot formed and the surface of the surface of the external electrodes 20a and 20 b.

When the organic compound 14 is adhered to the surface of the multilayerceramic capacitor 100, the organic compound 14 may directly contact tothe surface or the organic compound 14 and may be adhered to the surfacethrough another film or the like. The same thing is applied to thefollowing description.

In the embodiment, by a thermal analysis, it is confirmed that theorganic compound 14 having the siloxane bonding is a small moleculecyclic siloxane which is a cyclic siloxane from D3 to D20. For example,the small molecule cyclic siloxane D3 is trimer of the cyclic siloxanewhich is a solid substance of hexamethyl cyclotrisiloxane (C⁶H₁₈O₃Si₃).A boiling point of the small molecule cyclic siloxane D3 is 134 degreesC. The small molecule cyclic siloxane D4 is tetramer of the cyclicsiloxane which is semi-solid substance of octamethyl cyclotetrasiloxane(C₈H₂₄O₄Si₄). A boiling point of the small molecule siloxane D4 is 175degrees C.

The organic compound 14 releases the small molecule cyclic siloxane Dn(n≥3) at a relatively high temperature. Therefore, the small moleculecyclic siloxane Dn tends to be left after mounting the multilayerceramic capacitor 100 with solder. The small molecule cyclic siloxanehas water-repellent characteristic. Therefore, even if the multilayerceramic capacitor 100 is used in high-temperature and high-humiditycondition, adhesion of water to the surface of the multilayer ceramiccapacitor 100 is suppressed. It is therefore possible to improve thereliability of the multilayer ceramic capacitor 100.

Even if the organic compound 14 is adhered to the surface of theexternal electrodes 20 a and 20 b, degradation of wettability of thesolder is suppressed. The organic compound 14 is a coated article ofwhich a molecule amount is small. Even if the organic compound 14 iscoated on the Sn-plated layer (external electrode), the organic compound14 does not have a large influence on melting of the solder. Therefore,even if the organic compound 14 is adhered to the surface of theexternal electrodes 20 a and 20 b, mounting characteristic can beachieved.

A region of the surface of the multilayer ceramic capacitor 100 to whichthe organic compound 14 is adhered is not limited. It is preferable thatthe organic compound 14 is adhered to at least a part of a regionbetween the external electrode 20 a and the external electrode 20 b onthe upper face, the lower face and the two side faces of the multilayerchip 10. This is because the adhesion of water to the surface of themultilayer chip 10 between the external electrode 20 a and the externalelectrode 20 b is suppressed, and the migration is suppressed.

Alternatively, it is preferable that the organic compound 14 covers thewhole of the multilayer ceramic capacitor 100. This is because adhesionof water to the whole of the multilayer ceramic capacitor 100 issuppressed.

When the process for bonding the organic compound 14 to the surface ofthe multilayer ceramic capacitor 100 is adjusted, the temperature atwhich the small molecule cyclic siloxane Dn (n≥3) is released from theorganic compound 14 can be increased. And so, it is preferable that thesmall molecule cyclic siloxane Dn (n≥3) is not released at a temperatureless than 300 degrees C. and the small molecule cyclic siloxane Dn (n≥3)is released at a temperature which is equal to or more than 300 degreesC. It is preferable that there is at least one peak of released amountof the small molecule cyclic siloxane Dn (n≥3) at the temperature whichis equal to or more than 300 degrees C. When there are a plurality ofpeaks (local maximum values of the released amount) of the releasedamount of the small molecule cyclic siloxane Dn (n≥3) at temperatureswhich are equal to or more than 300 degrees C., it is preferable thatthere is a maximum released amount peak from 320 degrees C. to 480degrees C. In this case, when the multilayer ceramic capacitor 100 ismounted with solder at a temperature less than 300 degrees C., a largeramount of the small molecule cyclic siloxane Dn (n≥3) detected by thethermal analysis tends to be left in the organic compound 14.

When the amount of the organic compound 14 adhered to the multilayerceramic capacitor 100 is excessively small, sufficient water-repellentcharacteristic may not be necessarily achieved. And so, it is preferablethat the amount of the released small molecule cyclic siloxane Dn (n≥3)has a lower limit. For example, it is preferable that the amount of theorganic compound 14 adhered to the surface of the multilayer ceramiccapacitor 100 is large such that 0.50 ppm or more of the small moleculecyclic siloxane D3 is released per a unit area (cm²) of the surface ofthe multilayer ceramic capacitor 100 from 300 degrees C. to 600 degreesC. It is more preferable that the amount of the organic compound 14adhered to the multilayer ceramic capacitor 100 is large such that 2.0ppm or more of the small molecule cyclic siloxane D3 is released per aunit area (cm²) of the surface of the multilayer ceramic capacitor 100.

On the other hand, when the amount of the organic compound adhered tothe multilayer ceramic capacitor 100 is excessively large, it may bedifficult to mount the multilayer ceramic capacitor 100 on a substrate.And so, it is preferable that the released amount of the small moleculecyclic siloxane Dn (n≥3) has an upper limit. For example, it ispreferable that the amount of the organic compound 14 adhered to thesurface of the multilayer ceramic capacitor 100 is small such that 30ppm or less of the small molecule cyclic siloxane D3 is released per aunit area (cm²) of the surface of the multilayer ceramic capacitor 100from 300 degrees C. to 600 degrees C. It is more preferable that theamount of the organic compound 14 adhered to the multilayer ceramiccapacitor 100 is small such that 25 ppm or less of the small moleculecyclic siloxane D3 is released per a unit area (cm²) of the surface ofthe multilayer ceramic capacitor 100.

As illustrated in FIG. 4 , it is preferable that a silane film 15 isprovided on the surface of the multilayer ceramic capacitor 100, and theorganic compound 14 is adhered on the silane film 15. That is, it ispreferable that the silane film 15 is provided on at least a part of theregion including the surface of the multilayer chip 10 where theexternal electrodes 20 a and 20 b are not provided and the surface ofthe external electrodes 20 a and 20 b, and the organic compound 14 isadhered on the silane film 15. With the structure, the organic compound14 is strongly bonded to the surface of the multilayer ceramic capacitor100, by silane coupling effect. Therefore, the releasing of the smallmolecule cyclic siloxane Dn (n≥3) from the organic compound 14 issuppressed at a temperature less than 300 degrees C., as in the case ofa thermal analysis result of “impregnation+contact heating” of FIG. 8described later.

Next, a description will be given of a manufacturing method of themultilayer ceramic capacitor 100. FIG. 5 illustrates a manufacturingmethod of the multilayer ceramic capacitor 100.

Making Process of Raw Material Powder

A dielectric material for forming the dielectric layer 11 is prepared.Generally, an A site element and a B site element are included in thedielectric layer 11 in a sintered phase of grains of ABO₃. For example,BaTiO₃ is tetragonal compound having a perovskite structure and has ahigh dielectric constant. Generally, BaTiO₃ is obtained by reacting atitanium material such as titanium dioxide with a barium material suchas barium carbonate and synthesizing barium titanate. Various methodscan be used as a synthesizing method of the ceramic structuring thedielectric layer 11. For example, a solid-phase method, a sol-gelmethod, a hydrothermal method or the like can be used. The embodimentmay use any of these methods.

An additive compound may be added to resulting ceramic powders, inaccordance with purposes. The additive compound may be an oxide of Mg(magnesium), Mn (manganese), V (vanadium), Cr (chromium) or a rare earthelement (Y (yttrium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb(terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium) andYb (ytterbium)), or an oxide of Co (cobalt), Ni, Li (lithium), B(boron), Na (sodium), K (potassium) and Si, or glass.

In the embodiment, it is preferable that ceramic particles structuringthe dielectric layer 11 are mixed with compound including additives andare calcined in a temperature range from 820 degrees C. to 1150 degreesC. Next, the resulting ceramic particles are wet-blended with additives,are dried and crushed. Thus, ceramic powder is obtained. For example, itis preferable that an average grain diameter of the resulting ceramicpowder is 50 nm to 300 nm from a viewpoint of thickness reduction of thedielectric layer 11. The grain diameter may be adjusted by crushing theresulting ceramic powder as needed. Alternatively, the grain diameter ofthe resulting ceramic power may be adjusted by combining the crushingand classifying.

Stacking Process

Next, a binder such as polyvinyl butyral (PVB) resin, an organic solventsuch as ethanol or toluene, and a plasticizer are added to the resultingdielectric material and wet-blended. With use of the resulting slurry, astrip-shaped dielectric green sheet with a thickness of 0.8 μm or lessis coated on a base material by, for example, a die coater method or adoctor blade method, and then dried.

Next, metal conductive paste for forming an internal electrode is coatedon the surface of the dielectric green sheet by screen printing orgravure printing. The metal conductive paste includes an organic binder.Thus, a pattern for forming an internal electrode layer is provided. Asco-materials, ceramic particles are added to the metal conductive paste.A main component of the ceramic particles is not limited. However, it ispreferable that the main component of the ceramic particles is the sameas that of the dielectric layer 11.

Then, the dielectric green sheets are alternately stacked while the basematerial is peeled so that the internal electrode layers 12 and thedielectric layers 11 are alternated with each other and the end edges ofthe internal electrode layers 12 are alternately exposed to both endfaces in the length direction of the dielectric layer 11 so as to bealternately led out to the pair of external electrodes 20 a and 20 b ofdifferent polarizations. For example, a total number of the stakeddielectric green sheets is 100 to 500.

After that, a cover sheet to be the cover layer 13 is cramped on themultilayer structure of the dielectric green sheets. And another coversheet to be the cover layer 13 is cramped under the multilayerstructure. Thus, a ceramic multilayer structure is obtained. After that,the binder is removed from the ceramic multilayer structure (forexample, 1.0 mm×0.5 mm) in N₂ atmosphere of 250 degrees C. to 500degrees C.

Firing Process

The resulting compact is fired for ten minutes to 2 hours in a reductiveatmosphere having an oxygen partial pressure of 10⁻⁷ to 10⁻¹⁰ atm in atemperature range of 1100 degrees C. to 1300 degrees C. In this manner,it is possible to manufacture the multilayer ceramic capacitor 100.

Re-oxidizing Process

After that, a re-oxidizing process may be performed in N₂ gas atmospherein a temperature range of 600 degrees C. to 1000 degrees C.

Metal paste including a metal filler, a glass frit, a binder and asolvent is coated on the both end faces of the multilayer chip 10, andis dried. After that, the metal paste is baked. Thus, the ground layer21 is formed. The binder and the solvent vaporize by the baking. In themethod, it is preferable that the metal filler is Cu or the like. It ispreferable that the baking is performed for 3 minutes to 30 minutes in atemperature range of 700 degrees C. to 900 degrees C. It is morepreferable that the baking is performed for 5 minutes to 15 minutes in atemperature range of 760 degrees C. to 840 degrees C. After that, thefirst plated layer 22 may be formed on the ground layer 21 by plating.

Next, the conductive resin layer 23 is formed. For example, theconductive resin layer 23 is formed by immersion-coating thermosettingresin such as epoxy resin or phenol resin in which conductive fillerssuch as Ag, Ni, Cu or the like are kneaded, on the surface of the firstplated layer 22, and hardening the thermosetting resin by thermaltreatment. The thickness of the conductive resin layer 23 is notlimited. For example, the thickness of the conductive resin layer 23 isapproximately 10 μm to 50 μm. The thickness of the conductive resinlayer 23 may be determined in accordance with the size of the multilayerceramic capacitor 100. After that, the second plated layer 24 and thethird plated layer 25 are formed on the conductive resin layer 23 byelectroplating or the like.

Impregnation Process

Next, the silane film 15 is formed on the surface of the multilayerceramic capacitor 100, by impregnation of silane coupling agent.However, the impregnation process may not be necessarily performed.

Contact Heating Process

Next, silicon rubber is heated to 120 degrees C. or more and iscontacted to the surface of the multilayer ceramic capacitor 100. Thus,it is possible to bond the organic compound 14 to at least a part of theregion including the region of the surface of the multilayer chip 10where the external electrodes 20 a and 20 b are not provided and thesurface of the external electrodes 20 a and 20 b. When the impregnationprocess is performed, the organic compound 14 is adhered on the silanefilm 15.

In the manufacturing method of the embodiment, the organic compound 14is adhered to at least a part of the region including the region of thesurface of the multilayer chip 10 where the external electrodes 20 a and20 b are not formed and the surface of the surface of the externalelectrodes 20 a and 20 b. The organic compound 14 releases the smallmolecule cyclic siloxane Dn (n≥3) at a relatively high temperature.Therefore, the small molecule cyclic siloxane Dn tends to be left aftermounting the multilayer ceramic capacitor 100 with solder. The smallmolecule cyclic siloxane has water-repellent characteristic. Therefore,even if the multilayer ceramic capacitor 100 is used in high-temperatureand high-humidity condition, adhesion of water to the surface of themultilayer ceramic capacitor 100 is suppressed. It is therefore possibleto improve the reliability of the multilayer ceramic capacitor 100.

When the silicon rubber is heated to 120 degrees C. or more and iscontacted to the surface of the multilayer ceramic capacitor 100, thetemperature at which the small molecule cyclic siloxane Dn (n≥3) isreleased from the organic compound 14 is 300 degrees C. or more.

The ground layer 21 may be fired together with the multilayer chip 10.In this case, as illustrated in FIG. 6 , the binder is removed from theceramic multilayer structure in N₂ atmosphere of 250 degrees C. to 500degrees C. After that, metal paste including a metal filler, aco-material, a binder and a solvent is coated on the both end faces ofthe ceramic multilayer structure by a dipping method or the like and isdried. After that, the metal paste is fired together with the ceramicmultilayer structure. Firing condition is described in theabove-mentioned firing process. After that, a re-oxidizing process maybe performed in N₂ gas atmosphere in a temperature range of 600 degreesC. to 1000 degrees C. After that, the first plated layer 22 is formed onthe ground layer 21 by plating. Next, the conductive resin layer 23 isformed on the first plated layer 22. After that, the second plated layer24 and the third plated layer 25 are formed on the conductive resinlayer 23 by electroplating or the like.

As illustrated in FIG. 7 , the multilayer ceramic capacitors 100 may bemounted on a substrate 16 before bonding the organic compound to themultilayer ceramic capacitors 100. A sheet 17 of the silicon rubber maybe heated and may be pressed to the multilayer ceramic capacitors 100.Thereby, the organic compound 14 may be adhered to at least a part ofthe region including the region of the surface of the multilayer chip 10where the external electrodes 20 a and 20 b are not provided and thesurface of the external electrodes 20 a and 20 b. In this case, theorganic compound 14 is adhered to the substrate 16. It is thereforepossible to suppress breakdown caused by condensation on the surface ofthe substrate 16. It is possible to suppress defect of mounting, becausethe multilayer ceramic capacitors 100 are mounted before pressing thesheet 17 of the silicon rubber to the multilayer ceramic capacitors 100.It is preferable that an apparent density of the sheet 17 of the siliconrubber is 0.75 g/cm³ or less. This is because, when the apparent densityof the silicon rubber is large, the sheet 17 is hardened. And, when theapparent density of the silicon rubber is large and the sheet 17 ispressed to the multilayer ceramic capacitor 100, it is not possible tosufficiently cover the chips with the sheet 17. And, when the sheet 17having a large apparent density is pressed so as to cover the chips,excessive force is applied to the chips and the chips may be damaged.The apparent density is mass of the sheet 17 with respect to the volumeof the sheet 17.

In the embodiments, the multilayer ceramic capacitor is described as anexample of ceramic electronic devices. However, the embodiments are notlimited to the multilayer ceramic capacitor. For example, theembodiments may be applied to another electronic device such as varistoror thermistor.

EXAMPLES

The multilayer ceramic capacitors in accordance with the embodiment weremade and the property was measured.

Examples 1 to 6

An organic binder was kneaded with ceramic powder, of which a maincomponent was barium titanate, having reduction resistant. Thus, slurrywas prepared. The slurry was formed into a sheet by doctor blade. Thus,a dielectric green sheet was made. Metal conductive paste of Ni having apredetermined pattern was coated the dielectric green sheet by screenprinting. Thus, an internal electrode pattern was formed. The dielectricgreen sheet on which the internal electrode pattern was formed wasstamped into a predetermined size. And a predetermined number of thedielectric green sheets were stacked. And a ceramic multilayer structurewas made by thermos-compression.

Next, the ceramic multilayer structure was cut into predetermined chipsizes and was divided. Metal paste including a co-material was coated onthe both end faces of the ceramic multilayer structure (faces exposed toexternal electrodes) by an immersion method so that the metal paste hasa predetermined electrode width (E size).

Next, the resulting ceramic multilayer structure was fired at a 1250degrees C. in nitrogen or hydrogen atmosphere and was subjected to apredetermined thermal treatment. Thus, the ground layer 21 covering themultilayer chip 10 and the both end faces of the multilayer chip 10.Next, the surface of the ground layer 21 was subjected to dry polishingwith use of “whitemorundum” (registered trademark) as a polishing agent.After that, the first plated layer 22 was formed by Cu-plating. Next,conductive resin paste of which viscosity was adjusted to apredetermined value (10 to 30 Pa·s) was coated on the surface of thefirst plated layer 22 by an immersion method. Epoxy resin in which an Agfiller was kneaded was used as the conductive resin paste. After that,the conductive resin layer 23 was formed by hardening the conductiveresin paste by a thermal treatment. And, the second plated layer 24 andthe third plated layer 25 were formed on the conductive resin layer 23by Ni-plating and Sn-plating. The resulting multilayer ceramic capacitor100 had a length of 3.2 mm, a width of 2.5 mm and a height of 2.5 mm.

In the examples 1 to 4, silicon rubber was heated together with themultilayer ceramic capacitor 100. And the silicon rubber was contactedto the surface of the multilayer ceramic capacitor 100. Thus, theorganic compound 14 was adhered to the surface of the multilayer ceramiccapacitor 100. In the example 1, the heating temperature of the siliconrubber was 120 degrees C. In the example 2, the heating temperature ofthe silicon rubber was 150 degrees C. In the example 3, the heatingtemperature of the silicon rubber was 180 degrees C. In the example 4,the heating temperature of the silicon rubber was 210 degrees C.

In the examples 5 and 6, the silane film 15 was formed on the surface ofthe multilayer ceramic capacitor 100 by the impregnation process of thesilane coupling agent. After that, silicon rubber was heated togetherwith the multilayer ceramic capacitor 100. And the silicon rubber wascontacted to the multilayer ceramic capacitor 100. Thus, the organiccompound 14 was adhered to the surface of the multilayer ceramiccapacitor 100. In the example 5, the heating temperature of the siliconrubber was 150 degrees C. In the example 6, the heating temperature ofthe silicon rubber was 210 degrees C.

In the comparative example, the silane film 15 was not formed. Moreover,the organic compound 14 was not adhered (without water-repellentprocess).

With respect to the multilayer ceramic capacitors 100 of the examples 1to 6 and the comparative example, it was confirmed whether the smallmolecule cyclic siloxane Dn (n≥3) was released. The multilayer ceramiccapacitors 100 were heated from a room temperature to 600 degrees C.,and the component of the gas and the released amount from the mass ofthe released gas were analyzed, by gas chromatograph quadrature massspectrometry: GC-MS (Gas Chromatography Mass Spectrometry) (MPS2-xt madeby GERSTER/GC7890B/5977A MSD made by Agilent). FIG. 8 illustratesanalyzed results of the cyclic siloxane.

Analysis condition was as follows.

[Heating Desorption Condition]

40  degrees  C.  (0.5  minute) → 60  degrees  C./minute → 300  degrees  C. (30  minutes)cooling  condition: − 100  degrees  C. (0.5  minute) → 12  degrees  C./second → 320  degrees  C.  (5  minutes)[Gas Chromatograph Condition]

separation  column:DB-1Ms  (made  by  Agilent)temperature  elevation  condition  : 60  degrees  C.(5  minutes) → 10  degrees  C./minute → 310  degrees  C.(4  minutes)[Mass Analysis Condition]

-   -   ionization method: electron ionization    -   measured mass range: m/z=20 to 800        [Quantifying Method]        Relative concentration was used by using        decamethylcyclopentasiloxane (pentamer of cyclic siloxane).

As illustrated in FIG. 8 , in the comparative example, releasing of thesmall molecule cyclic siloxane was not observed. It is thought that thiswas because the silicon rubber was not contacted to the multilayerceramic capacitor 100. On the other hand, in the examples 1 to 6, thereleasing of the small molecule cyclic siloxane was observed at atemperature which was equal to or more than 300 degrees C. It is thoughtthat this was because the silicon rubber was contacted to the multilayerceramic capacitors 100. The small molecule cyclic siloxane was acompound having siloxane bonding. It is thought that the cyclic siloxanewas not released at a temperature which was less than 300 degrees C.because the silicon rubber was contacted to the surface of themultilayer ceramic capacitor 100 and the cyclic siloxane was releasedafter a part of bonding of the organic compound 14 having the siloxanebonding was broken.

In the examples 1 to 4, the releasing of the small molecule cyclicsiloxane was observed at a temperature which was equal to 300 degrees C.or more. And, the releasing of the small molecule cyclic siloxane washardly observed at a temperature which was approximately 400 degrees C.or more. The released amount peak was observed at a temperature whichwas equal to 300 degrees C. or more. On the other hand, in the examples5 and 6, the releasing of the small molecule cyclic siloxane was widelyobserved from 300 degrees C. to 550 degrees C. It is thought that thiswas because the organic compound having the siloxane bonding wasstrongly bonded to the silane film on the surface of the multilayerceramic capacitor 100 because the silane film 15 was formed.

Next, in the examples 1 to 6, it was confirmed whether the smallmolecule cyclic siloxane Dn (n≥3) was released from 300 degrees C. to600 degrees C., with respect to other samples. Table 1 shows theanalyzed result of the example 2. As shown in Table 2, it was confirmedthat a quantitative value of the released amount of the small moleculecyclic siloxane of D3 to D20 was obtained. When the value of “n” wassmaller, the released amount was larger. It is thought that this wasbecause when the value of “n” was smaller, the molecular weight wassmaller.

TABLE 1 QUANTITATIVE VALUE CYCLIC SILOXANE ppm (w/w) TRIMER D3  2.3TETRAMER D4  0.5 PENTAMER D5  <0.1 HEXAMER D6  <0.1 HEPTAMER D7  <0.1OCTAMER D8  <0.1 NONAMER D9  <0.1 DECAMER D10 <0.1 UNDECAMER D11 <0.1DODECAMER D12 <0.1 TRIDECAMER D13 <0.1 TETRADECAMER D14 <0.1PENTADECAMER D15 <0.1 HEXADECAMER D16 <0.1 HEPTADECAMER D17 <0.1OCTADECAMER D18 <0.1 NONEDECAMER D19 <0.1 ICOSAMER D20 <0.1

Next, 400 samples were subjected to a mounting test, with respect toeach of the examples 1 to 6 and the comparative example. In the mountingtest, a reflow furnace of which a maximum temperature was 270 degrees C.or more was used. And, an external view was observed with respect toeach sample. When the crawling angle of the edge of the solder filletwas less than 90 degrees with respect to the edge face of the externalelectrode, it was determined as acceptance. When the crawling angle was90 degrees or more, it was determined as non-acceptance. A ratio ofsamples determined as non-acceptance was measured with respect to 400samples.

Next, other 400 samples were subjected to a humidity resistance test,with respect to each of the examples 1 to 6 and the comparative example.In the humidity resistance test, each sample was left under a conditionat a temperature of 120 degrees C. and at a relative humidity of 85%.And, a voltage of 1.5 times as much as a rated voltage was applied toeach sample for 100 hours. And an electrical value (insulatingresistance between electrodes) was measured. When the insulatingresistance×a capacity was 100 MΩ·μF or more, it was determined asacceptance. When the insulating resistance×the capacity was less than100 MΩ·μF, it was determined as non-acceptance. A ratio of samplesdetermined as non-acceptance was measured with respect to 400 samples.

Next, other 400 samples were subjected to a condensation test, withrespect to each of the examples 1 to 6 and the comparative example. Thesamples were mounted on reliable substrates (CEM 3). The samples wereput in a thermo-hygrostat tank. And, 16 V was applied to the samples. Acondensation test program of JIS 60068-2-30 was performed 6 times. Afterthat, it was confirmed whether the migration occurred or not. Thecondition of each cycle of the program is as follows. (1) The humiditywas kept at 98%. The temperature was changed from 25 degrees C. to 55degrees C. for 3 hours. (2) The temperature was kept at 55 degrees C.The humidity was changed from 98% to 93% for 15 minutes. (3) Thetemperature was kept at 55 degrees C. and the humidity was kept at 93%for 9 hours and 25 minutes. (4) The humidity was kept at 93%. Thetemperature was changed from 55 degrees C. to 25 degrees C. for threehours. (5) The temperature was kept at 25 degrees C. and the humiditywas kept at 93% for 3 hours. (6) The temperature was kept at 25 degreesC. The humidity was changed from 93% to 98% for 5 hours and 30 minutes.Each sample was observed by a stereomicroscope of 40 magnifications. Andit was determined whether there was a precipitate between externalelectrodes. When there was a precipitate, it was determined that themigration occurred. A ratio of samples in which the migration occurredwas measured with respect to 400 samples.

Table 2 shows the released amount of the small molecule cyclic siloxaneD3 from 300 degrees C. to 600 degrees C. and results of the mountingtest, the humidity resistance test and the condensation test. As shownin Table 2, the releasing of the small molecule cyclic siloxane D3 wasnot observed in the comparative example. It is thought that this wasbecause the silicon rubber was not contacted to the multilayer ceramiccapacitor 100. Next, the releasing of the small molecule cyclic siloxaneD3 was observed, in the examples 1 to 6. It is thought that this wasbecause the silicon rubber was heated and contacted to the multilayerceramic capacitor 100.

TABLE 2 COMPARATIVE WITHOUT SILANE WITH SILANE EXAMPLE EXAMPLE 1 EXAMPLE2 EXAMPLE 3 EXAMPLE 4 EXAMPLE 5 EXAMPLE 6 HEATING UNPROCESSED 120 150180 210 150 210 TEMPERATURE [° C.] RELEASED 0 0.46 2.17 9.41 23.89 3.7429.76 AMOUNT OF D3 [ppm/cm²] MOUNTING 0/400 0/400 0/400 0/400 0/4000/400 2/400 TEST HUMIDITY 7/400 2/400 0/400 0/400 0/400 0/400 0/400 TESTCONDENSATION 23/400  3/400 0/400 0/400 0/400 0/400 0/400 TEST

The descending order of the released amount of the small molecule cyclicsiloxane D3 was the example 1, the example 2, the example 3 and theexample 4. It is thought that this was because the amount of the organiccompound adhered to the samples was larger when the heating temperatureof the silicon rubber was higher. Similarly, the released amount of thesmall molecule cyclic siloxane D3 of the example 6 was larger than thatof the example 5. It is also thought that this was because the amount ofthe organic compound adhered to the samples was larger when the heatingtemperature of the silicon rubber was higher.

Next, the non-acceptance rate of the mounting test was low in theexamples 1 to 6 and the comparative example. It is thought that this wasbecause the released amount of the low molecule cyclic siloxane D3 perunit area was 30 ppm/cm′ or less. It was confirmed that it waspreferable that the released amount of the low molecule cyclic siloxaneD3 per unit area was 25 ppm or less, because there were no samplesdetermined as non-acceptance in the examples 1 to 5.

Next, in the comparative example, the non-acceptance rate of thehumidity resistance test was high. On the other hand, in the examples 1to 6, the non-acceptance rate of the humidity resistance test was low.It is thought that this was because the water-repellent characteristicwas achieved because the organic compound 14 was formed. It wasconfirmed that it was preferable that the heating temperature of thesilicon rubber was 150 degrees C. or more, because there were no samplesdetermined as non-acceptance in the examples 2 to 6.

Next, non-acceptance rate of the condensation test of the comparativeexample was high. On the other hand, the non-acceptance rate of thecondensation test was low in the examples 1 to 6. It is thought thatthis was because the water-repellent characteristic was achieved becausethe organic compound 14 was formed. It was confirmed that it waspreferable that the heating temperature of the silicon rubber was 150degrees C. or more, because there were no samples determined asnon-acceptance in the examples 2 to 6.

Although the embodiments of the present invention have been described indetail, it is to be understood that the various change, substitutions,and alterations could be made hereto without departing from the spiritand scope of the invention.

What is claimed is:
 1. A manufacturing method of a ceramic electronicdevice comprising: preparing a ceramic electronic device having amultilayer chip, a first external electrode and a second externalelectrode, and bonding an organic compound having a siloxane bonding toat least a part of a region including a surface of the multilayer chipwhere neither the first external electrode nor the second externalelectrode is formed and surfaces of the first external electrode and thesecond external electrode, by contacting heated silicon rubber to theregion, wherein the multilayer chip has a structure in which each of aplurality of dielectric layers and each of a plurality of internalelectrode layers are alternately stacked, a main component of thedielectric layers being ceramic, the multilayer chip having arectangular parallelepiped shape, the plurality of internal electrodelayers being alternately exposed to a first end face and a second endface of the multilayer chip, the first end face facing with the secondend face, wherein the first external electrode is provided on the firstend face, therein the second external electrode provided on the secondend face.
 2. The method as claimed in claim 1, wherein the organiccompound is adhered to at least the part of the region including thesurface of the multilayer chip where neither the first externalelectrode nor the second external electrode is formed and the surfacesof the first external electrode and the second external electrode, bymounting the ceramic electronic device on a substrate before the organiccompound is adhered and contacting the heated silicon rubber to theceramic electronic device.
 3. The method as claimed in claim 1, whereinthe silicon rubber that is heated to 120 degrees C. or more is contactedto the region including the surface of the multilayer chip where neitherthe first external electrode nor the second external electrode is formedand the surfaces of the first external electrode and the second externalelectrode.
 4. The method as claimed in claim 1 further comprising:forming a silane film on the ceramic electronic device before theorganic compound is adhered by impregnation of a silane coupling agentto the ceramic electronic device, wherein the organic compound isprovided on the silane film.